For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:

Vehicle Care
California Proposition 65 WarningInstallation Procedure
Create 5 x 18 mm (4/16 x 11/16 in) slots for MIG-Brazing along the edges
of the front wheelhouse panel rear reinforcement as
noted from the original panel.
Create a 5 x 18 mm (4/16 x 11/16 in) slot for MIG-Brazing where front
wheelhouse front panel and front wheelhouse panel ...
Headlamp Aiming Procedure
Open the hood.
Measure from the floor to the center of the headlamp bulb. Some
headlamps have an aim dot marked on the headlamp lens.
At the screen, measure from the floor and place the horizontal tape at
the measured distance.
Measure from the reference line on the floor to the le ...
Metric Fasteners
This vehicle provides fastener dimensions using the metric system. Most
metric fasteners are approximate in diameter to equivalent
English fasteners. Make replacements using fasteners of the same nominal
diameter, thread pitch, and strength.
A number marking identifies the OE metric fastener ...